Portable cooking devices are well known in the art. Such devices find utility in “backyard” barbecues, in camping and recreational environments, and in preparing meals for military personnel on field operations, displaced persons in refugee camps, and victims of storms. A modern-day field burner should be capable of utilizing a variety of fuels, including gasoline, kerosene, ethanol, methanol, diesel, and aircraft jet fuels, such as JP-4, JP-5, JP-7, and JP-8. For modern day field operations, JP-8 is preferred for its high boiling point and low volatility and for its safer handling and transportation, as compared with more volatile fuels. The fact that JP-8 is already used as a ground and air transport fuel makes it desirable to be used more generally in other operations, such as for heating and cooking. On the other hand, JP-8 has one of the highest boiling point ranges, specifically a boiling point range between about 166° C. (330° F.) and about 277° C. (530° F.), which makes JP-8 among the most difficult fuels to vaporize. Moreover, JP-8 tends to soot and therefore is one of the most difficult fuels with which to achieve clean combustion.
U.S. Pat. No. 7,380,548 B2 (hereinafter “Ryan”) discloses a stove operating on diesel fuel and suitable for field operations. The stove consists of a frame bounding an area to receive, among other elements, a burner and a heating cavity assembly. A diffuser plate is mounted on the heating cavity assembly and covers an open top portion thereof, the diffuser plate being configured to receive heated gases rising from the burner, and to distribute said heated gases evenly proximate an upper surface of the diffuser plate. A griddle plate is mounted above the diffuser plate as a cooking surface.
U.S. Pat. No. 6,176,233 B1 (hereinafter “Babington”) discloses a powered multi-fuel burner for heating a heating cabinet of a cooking station useful in field operations. Babington discloses use of a variety of fuels, including JP-8. More specifically, Babington discloses a frame that may be positioned in an existing heating cabinet of a field cooking facility, such as an M-59 Field Range Heating Cabinet. A heat plenum is located at one end of the frame, the front side of the heat plenum receiving a flame tube from a burner assembly. The top of the heat plenum has an aperture surface which functions as a flame spreader, emitting hot gases, but no flame, to produce cooking heat without producing soot on adjacent surfaces
U.S. Pat. No. 4,773,847 B1 (hereinafter “Shukla”) discloses a liquid diesel-fueled thermoelectric field burner suitable for field operations. As seen from FIG. 1 of Shulka, a rechargeable battery powers the initial start-up which atomizes the liquid fuel; then simultaneous excitation of a glow coil triggers combustion which propagates throughout a preheat burner. Finally, a preheated vaporized mixture of fuel and air are combusted in a main burner under blue flame; and the heat of combustion is transferred by radiation and convection of hot combustion gases to a cooking load.
The aforementioned cooking apparatuses disclosed by Ryan, Babington, and Shukla require a flame burner, which results in inefficient heat transfer, excess consumption of fuel and oxidant, and unacceptably high emissions of carbon monoxide and incompletely oxidized hydrocarbons. Such apparatuses cannot readily be used indoors.
Other art teaches flameless cooking appliances; for example, U.S. Pat. No. 5,655,437 (hereinafter “Vitacca”) teaches a flameless charcoal burner system that prevents flames from singeing food or flaring toward the user. As best can be described, the burner employs heated charcoals in a side burner system that is in a spaced-apart relation to the cooking grill, the grill being heated by hot gas convection. The apparatus is useful as a “back-yard” barbecue device, but not under field operations with liquid fuels.
Another flameless barbecue grill is disclosed in U.S. Pat. No. 3,931,805 (hereinafter “Nelson”), comprising a surface for supporting food and a burner assembly positioned below in spaced-apart relation to the food supporting surface. The assembly includes a plurality of burner elements that provides a flameless incandescent heating area when supplied with an ignited mixture of gaseous fuel and air. Nelson disadvantageously employs a gaseous fuel under ignition conditions and cannot operate with liquid fuels.
U.S. Pat. No. 4,138,220 (hereinafter “Davies”) discloses a flameless apparatus for catalytically oxidizing grease, fats, oils, and/or other hydrocarbons in rising fumes from cooking processes. The apparatus involves catalytic post-combustion of waste gas and is neither intended nor useful for cooking food.
Finally, flameless oven broilers are well known as taught, for example, in U.S. Pat. No. 4,473,004 (hereinafter “Wells”), wherein thermoelectric elements overhead of a cooking surface proceed to cook food via radiant infrared heat.
Among teachings to other kinds of flameless combustion devices, which disclosures do not explicitly mention cooking, there is found U.S. Pat. No. 4,180,384 (hereinafter “Rice”), which teaches a vaporized fuel consisting of a “lower alcohol” or “lower ether or hydrocarbon,” being passed with air in downflow direction through a catalyst bed consisting of solid porous pellets containing high and low concentrations of platinum family metals deposited on a support, such as alumina or sieves, with resulting catalytic combustion. Hot combustion gases exit through a surface containing a plurality of apertures or openings.
In view of the above, the art needs an improved flameless cooking appliance that is robust, portable, useful in field operations, and adaptable for use with liquid fuels, desirably, JP-8 fuel. Additionally, the flameless cooking appliance should provide acceptably low exhaust emissions such that the appliance can be safely used in indoor applications.